Gore only uses physical attacks, so make up a party that is resistant to it (Rs, Rf, or Ab physical). Spam wind-based attacks to trigger Devil COOP (it pierces Rf physical). Once Gore used Charge, his next attack will target at the MC, have MC defend the next turn or use item/magic to reflect the damage, otherwise it will be about 1000 worth of damage if he uses Adaptation. Assistant spells like Tarukaja and Rakunda are also useful.

Obtain Clement Bell (クレメントベル). > Take it back to the lab and obtain main application Unlock D (アンロックD).

Configure the team so that most of the members can null light attacks (破魔無効). All attacks from Mastema are hit-all, so be prepared to use Mediarama or Mediarahan. Spam fire-based attacks to trigger Devil-COOP.

Wave of Death inflict damage to all targets. Megido Storm inflict electric damage to all target. Sinner's Song inflict almighty damage plus charm status ailment. Right Hand raises all parameter of the user's and recovers about 350 HP. Requiem is a hit-all instant death skill that is neither Hama nor Mudo properties and will not be stopped by Tetraja, but has low accuracy if Agility buff/debuffs are applied.

Requiem can penetrate Tetraja. Configure the MC to resist Elec and wear the Dragon Ring accessory for an effective second life. Try to bring demons with Dekaja to cancel the Right Hand buffs, and have ice, fire, and wind attacks available, since the boss' weaknesses shift around, seemingly at random.